Protective means for an electrical distributing system.



R. P. JACKSON.

PROTECTIVE MEANS FOR AN ELECTRICAL DISTRIBUTING SYSTEM.

APPLICATION FILED IULY I4. I9I5.

1,224,172. Patented May 1, 1917.

W a a a I IIIII'IIIIIIIIIIIII' /2 /3 WITNESSES: INVENTOR ATTORNEY or r :enscrerc srm Application filed Jinlgr 1 L,

o cw may it known that l, iler JAon'sorr, a

citizen of the United States, and. s resident of Edgewood Perl-r, in county of A gheny and of Pennsylrenie, have vented s new end'nsefnl lmprover Protective Means for Elect cal sting; System; oi which the following is a specification,

My invention relates to electri cl systerrs of distribution, and it hes special reterenc to distributing circuits which suppl pow-e toe plurality oi translating devices, sncli e incandescent lamps, and the like, connected, either singly or in 2 ries relationship with one 1/ posed st isoleted points in toe circu More perticnlsrly, my inv ntion r protective devices that are adapted be 1 in circiiits of ore-indies character in order to inst service and e c l c '1 trensrormers whic loin l "son the I lln alternating-current l employingiccendesce lam r-ectly in circuit and in s w h one another, it is cast means for closing the circui'; filament of an isol inca "when subjected to the momentar ly impressed suit or the mterruption end, to my knowledge, have never ployeol as protective devices for trans a ers which are connected in series relationship with one another in it distributing circuit. Again, automatic circuit closers heretofore employed have not been of such cotestruction as to permit them to be repeatedly used for similar service, but it has be n necessary to replace such devices, either Wholly or in part, before they he stored to their initial condition. y

distributing circuits or the char? Specification c1 Letters Patent.

. the circuit Serial E30, 327,???-

and time in restoring normal conditions in the circuit, While, the same time, the protective devices are entirely efiective for suppressing subsequent disturbances arising from further bnrnouts or breaks in the lamp filaments.

invention is designed for the accomplishment of these objects and other objects to he hereinsi" disclosed.

Figure l is adiagrammstic View of an e ternati gcurrent li 'nting circuit embodying ion; 2 is a plan View of e p" a device embodying a preferred n v nvention, and l 3 is s side y in section, of the device 1101*? 1, an alternating-curl 15 supplied 'th power source (not shown) At isolated points in s transformers 3 are disposed, the pr story windings l thereof being connected in series-circuit relationship with the main CliCl o, substantially as shown. Seconderv 5 of the transformers constitnce lOCfal circuits, each comprising a plura y of trsnsl ting devices or incandescent lamps 6 which are, in turn, conted in series relationship with one an other and with the secondary windings 5. The circuit 1, it is apparent, is commonly used in lighting systems embodying lowvoltage tungsten lamps which may be substituted arc lamps heretofore extensively employed in series lighting systems. ()1? course, it will he understood that each of the local circuits "II", comprising the secondary ings and the translating devices 6, urn-fish to single incandescent Referring rent series ci from any through the lamp only or to a plurality of them, as described.

Inasmuch as the filaments of the lamps 6 are liable to burn out or be broken, thereby interrupting the circuits through the secondary windings 5, it is important that protective means be provided for automatically and pern'ianently short-circuiting the secondary windings 5 when such interruptions occur. To this end, I provide protective devices 8 which comprise spaced spark-gap members 9 mounted upon an insulating base 10. The spark gap members 9 are adjustable thereby permitting the break-down strength of the resulting spark gaps to be regulated to the desired or predetermined voltages. It is well known that, when the circuit through the secondary winding of a series transformer is interrupted, the common magnetizable iron core member be comes magnetically saturated to a very high degree, by reason of the high current flowing through the primary winding thereof which, on this occasion, is equivalent to a high exciting current. The high magnetic saturation of the magnetic cores of series transformers, such as core members 11 of the transformers 3, induces very high and dangerous electromotive forces in the secondary windings 5, thereby subjecting the insulation of the windings to high-vole age stresses which are of such character as to substantially preclude uninterrupted service. In order to prevent the transformers 3 from burning out when such abnormal conditions obtain, the protective devices 8 are so adjusted that the spark gaps between the spaced terminals 9 will break down at less than the dangerous value of the abnormal voltages. For instance, the sparks gaps should be so adjusted as to break down at values less than 100% overvoltage. If a pr .ective device 8 is designed to continuously i stand 35 volts, which is common practice, it should be so adjusted as to break down and afford a permanent short circuit to its associat secondary winding 5 when 1500 volts a: impressed thereupon.

In Figs. 2 and protective device gap members 9 bers or screws w a preferred form of my illustrate -L The spark- :nstitute thr" Ich are proviccd with adjusting heads The shank pertions of the screws 9 attend through te inal blocks 13 which are secured to the ins ting base 10. By means of terminals I electrical connections made to the tective de vice. The shanks of the screw members LT: are provided with longitudinally extending openings 15., the members 9 being so disposeo that the openings 15 are adjacent to, l alinement with, each other. In o'giicnings 15, I place a body of plastic real of low fusibiiity such, for

ample, as a lead fuse wire. The openings 15 may be so drilled that standard fuse wire will snugly fit therein. The spark gap be tween the cooperative electrodes 9 may then be adjusted by any suitable gage, such as a copper plate. \Vhen the circuit comprising the secondary winding 5 is interrupted, the high electromotive force induced therein will effect a spark discharge between the electrodes 9 and the exposed surfaces of the metallic bodies 16 will constitute the arcing surfaces for sustaining these sparks. As a result, the arcs will cause the lead bodies 16 to melt and, as they flow from the openings 15, will unite to form a continuous electric path, thereby automatically and permanently short-circuiting the secondary winding It will be noted that, when are discharges of the above-mentioned character occur, the fusible bodies 16 contained in the openings 15 will melt together to form a homogeneous mass instead of burning back and increasing the length of the spark gap. This is an important feature since it insures maximum protection for the transformers 3. After the burned-out incandescent lamp has been replaced and the secondary circuit put into operative condition, the spark gap may be reset at the expenditure of only a small amount of labor and time. To illustrate, the electrodes 9 are unscrewed suiliciently to cause the union therebetween to break. The gage is then interposed between the arcing surfaces of the electrodes and the electrodes are subsequently tightcued to closely engage the spark gap gage. As a result, the bodies of metal. 16 are Loothed off at the arcing surfaces and f eed back into the openings 15, thereby reing the protective device 8 to its initial 4 o.

'hile I have shown and described, in do 1 one embodiment of my invention, it be apparent that many modifications ma be made therein without departing frrnn the spirit and scope of the appended claims.

I claim as my invention:

1. A protective device comprising adjust able spaced spark-gap members composed. of material of high fi'lsibility and provided with leiigitudinally extending openings, and bodies of metal of low fusibility disposed in said openings in the spark-gap members.

2. A protective device on ing a pair of similar and spaced sp 1D members composed of material of high ibility and. provided with longitudinall extending openings, and bodies of plastic metal of low provided with a longitudinal opening that is alined with a corresponding opening in the other member, and bodies of metal of low fusibility disposed in said openings.

4. A protective device comprising adjustable spaced spark-gap members that are recessed at their arcing ends, and bodies of metal of low fusibility disposed in said recessed ends.

In testimony whereof, I have hereunto 10 subscribed my name this 30th day of June, 1915.

RAY P. JACKSON. 

